The present invention relates to cutting implements, and more particularly to saw blades for a yieldable material.
Previously, when it was desired to cut a composite material such as a loose mat of oriented strand board in the uncured state it was conventional to use a rotating circular saw blade of conventional design. Oriented strand board is formed of elongated wood particles or chips and one or more binder ingredients. The mat while being loose in the uncured state is stiff and retains its shape while supported on a flat surface. Conventional saw blades have teeth extending outwardly from an outer circumferential rim of the saw blade. These teeth are formed with an outwardly extending cutting element that is designed to engage the material to be cut. When the conventional saw blade cuts through the full thickness of the loose mat, the blade will then cut into the surface of the carrier medium because there is no means of preventing the cutting surfaces on the teeth from engaging the carrier medium. As a result, the surface of the carrier medium such as the screen, belt or caul that carries the loose mat is damaged.
There have been several attempts in the past to design a blade for cutting yieldable materials such as fabric or uncured rubber. These prior art cutting blades are designed for very specific purposes and are structurally and operationally quite different from the present invention. None would be useful for cutting composite material such as oriented strand board. One such example of a prior art blade is shown in Rizer et al., U.S. Pat. No. 3,798,767 which is directed to a device for cutting flexible material such as carpet. In the device of Rizer et al. a blade 35 is provided having spaced semicircular shaped teeth with a smooth outer surface. The root portion 30 of the teeth have an inner surface 37 which is sharpened to act as the cutting surface with a cutting edge. Fabric such as carpet is pushed into the cutting blade and is sandwiched between the cutting blade 27 and block 15. As the device is advanced, material is pushed into the area between block 15 and the blade 37 by the outer surface 36 of the teeth 28. The material is then cut by the surface 37 and the surface 41. Blade 27 and block 15 act like a pair of shears in that one of the blades is a cutting blade and the other blade is a stationary blade which holds the material in place.
Sauer, U.S. Pat. No. 3,308,703 discloses another type of blade comprising a plate for grooving uncured rubber. The blade consists of an outer circumferential edge 13 which is beveled at 13a, 13b and 13c. The bevels are made such that they alternate in opposite directions of slope. Positioned between the teeth 12 are gullets 15. Gullets 15 are formed with side cutting edges 16 and 17. The Sauer device operates on uncured rubber which is a sticky soft material which can have reinforcing material contained within the sticky soft mass. The outer rim of bevel teeth 12 are sharpened to cut into the rubber and create a groove. Advancement of the blade is continued until it reaches the cording or reinforcing material which strengthens the rubber. The sharpened surfaces 16, 17 at the root portions are designed to cut and remove the cording from the groove without removing the remainder of the cording. That is to say that the rubber is grooved as the cording material is cut without disturbing the position of the reinforcing material in the uncured rubber.
Martinu, U.S. Pat. No. 4,133,361 discloses a device for machining and grooving composite material such as cured particle board. The device consists of a conical disk having a series of blades 62, 63 and 64 attached to the conical outward surface and a groove cutting bit 78 is attached at the center of the conical surface for grooving the composite material. This invention is intended to work on cured composite material which is in a hardened state. The device is designed to machine composite material boards such that joints can be formed easily and quickly.
Blake, U.S. Pat. No. 4,766,794 discloses a conventional rotary saw blade having carbide inserts 18 positioned on the outer surface of the cutting teeth. The cutting surfaces of the inserts 18 are provided at different radial positions such that the blade does not bind within the kerf.